+ /*
+ * subscribe/unsubscribe to object notifications
+ * The unsubscribe message is sent from ubusd when
+ * the object disappears
+ */
+ UBUS_MSG_SUBSCRIBE,
+ UBUS_MSG_UNSUBSCRIBE,
+
+ /*
+ * send a notification to all subscribers of an object.
+ * when sent from the server, it indicates a subscription
+ * status change
+ */
+ UBUS_MSG_NOTIFY,
+
+ UBUS_MSG_MONITOR,